Many oil wells must be pumped by locating a pump jack unit above the surface of the ground and operatively connecting said unit to a downhole pump by employment of a sucker rod string. The prior art sucker rod string is made up of a plurality of joints of solid metal rod which are either twenty-five or thirty feet in length, depending upon the geographical location of the oil field.
The oil bearing strata of the borehole may be located as much as several thousand feet below the surface of the earth and the sucker rod string therefore may be more than a mile in length. Accordingly, the weight of this quantity of sucker rod may be several thousands of pounds.
Boreholes are usually crooked for they corkscrew or spiral rather than extend precisely vertical because of the inherent problems associated with drilling. Accordingly, the sucker rods must be made relatively flexible so that the rod string can conform to the spiraling production tubing.
Since all boreholes inherently deviate a substantial amount from the vertical, the exterior of the sucker rod frequently contacts and rubs the production tubing at spaced, marginal, interior portions thereof, depending upon the amount of deviation. One prior art expedient which may be employed to reduce this undesirable problem associated with production is the provision of guide means attached to the rods. For example, Wolfe, U.S. Pat. No. 3,510,234 and Collett, U.S. Pat. No. 3,490,526, propose a guide means for reducing the wear between the rod and the interior of the production tubing.
Others have approached this wear problem by reducing the weight of the sucker rod string by employment of a single length of reinfored plastic as exemplified by Wiechowski, U.S. Pat. No. 3,889,579.
Wire rope and fittings therefor are known to those skilled in the art as evidenced by the patents to Trier et al., U.S. Pat. No. 3,100,924 and Matthews, U.S. Pat. No. 1,863,021. Reference is made to the above cited U.S. Patents as well as to the art of record therein for further background of this invention.
It would be desirable to have made available an actuating string for a downhole pump which is considerably reduced in weight, which is extremely flexible and accommodates itself to the deviation of a hole without suffering the deleterious effects normally associated with repeated bending moments, and which includes spaced guide means thereon for reducing the wear normally effected between the rod string and the interior wall of the production tubing.